Not Applicable.
The invention relates to concrete retaining wall blocks and to a form for manufacturing concrete retaining wall blocks.
Concrete blocks are sometimes used for constructing retaining walls. Generally rectangular blocks have been stacked to form a retaining wall and then back filled on one side to form a terrace. The backfill can exert a sufficient force on the retaining wall blocks to cause the stacked blocks to move out of their original position. In some cases, ground anchors or a geo grid system have been secured to the blocks to increase the stability of the wall. Retaining wall blocks have been stacked to form a stepped wall so that the front face of each row of blocks is offset slightly behind the front face of the adjacent lower row of blocks. According to the prior art, a raised lip has sometimes been formed along the upper edge of the block adjacent the front face to prevent the stepped blocks from sliding out of position, as shown in Arvai et al. U.S. Pat. No. 5,791,827. According to another prior art retaining wall block design, retaining wall blocks have sometimes been formed with a groove extending along a bottom surface parallel to an exposed face of the block and with a raised rib on a top surface. The groove on a stacked block receives the raised rib on the block below for aligning the front faces of the stacked blocks. Such an arrangement is shown, for example, in Forlini U.S. Pat. No. 5,647,185. Retaining wall blocks also may be formed with round knobs on the top surface which fit into a groove on the bottom surface of a stacked block to permit forming a curved retaining wall, as shown in Wagenaar U.S. Pat. No. 5,337,527.
Ready mix concrete companies mix batches of concrete to customers"" orders and deliver the mixed concrete in trucks to the customer""s construction site. It is customary for a concrete customer to order more concrete than it estimates that it will need for a job so that there will be adequate concrete available to finish the job. When a truck returns to the ready mix company from a delivery, it generally has some left over concrete which must be cleaned from the truck. The left over concrete is sometimes cast into various smaller articles. However, this can be labor intensive.
Ready mix concrete companies often have relatively simple forms for casting blocks from the left over concrete. Typically, the blocks are sufficiently crude in appearance that they are only suitable for forming retaining walls for applications such as for gravel and sand storage and for similar commercial applications. The blocks do not have an appearance which is suitable for constructing retaining walls for residential and upscale commercial applications where an attractive appearance is necessary. Blocks which are not needed are often disposed of in land fills.
It is preferable to pour left over concrete into forms which create usable products which can be sold, such as architecturally acceptable retaining wall blocks, so long as excessive labor is not required.
According to the invention, a form is provided for casting concrete retaining wall blocks. The form is simple to use and produces attractive blocks which can be sold for use in residential and commercial applications.
The retaining wall block form includes a bottom having a resilient face insert which forms a suitable textured front surface or face for the cast block. Therefore the blocks are cast in the form with face down. Four sides of the form are hinged at the bottom to pivot between a closed position and an open position. A locking mechanism holds the sides of the form in the closed position while casting a block. After the concrete block has sufficiently hardened, the locking mechanism is released and the form sides are pivoted away from the block to the open position to free the cast block for removal by lifting vertically from the open form. Removable inserts are attached to the sides of the form to create different types of blocks. For example, inserts may form a groove in a bottom surface of the block and to form one or more knobs in the upper surface of the block. The side of the form which shapes the top of the block also may include resilient inserts which form a recess in the top of cast block and which position a steel wire or rod in the block to extend across the recess. The embedded rod forms a lifting hook for use in moving and stacking the blocks when constructing a retaining wall.
The back surface of the cast block is the top surface of the concrete when poured into the form. One or more sides of the form may include a minimum fill mark for indicating when a minimum acceptable amount of concrete has been poured into the form. The form is sized to accommodate additional concrete since the amount of left over concrete will typically vary with each load. The blocks are designed to stack in tiers with the front faces of the blocks aligned to form a vertical retaining wall or with upper tiers slightly stepped back to form a sloping retaining wall. Differences in depth of the blocks are compensated for by allowing the blocks to extend different depths into the soil or back fill behind the wall. Preferably, a heavy wire loop is embedded into the block to extend above the top surface of the poured concrete in the form (the back surface of the block during use). The wire loop is used for lifting the block from the form after the concrete has hardened and the form is opened. The loop also may be used to secure to optional ground anchors or structural tie-backs to add stability to a retaining wall constructed from the blocks. However, such tie-backs will normally not be needed, unless the wall is quite high or the soil is unstable.
Various objects and advantages of the invention will become apparent from the following detailed description of the invention and the accompanying drawings.